University of Kentucky Research Examines Impact of Nighttime Light on Alzheimer's Disease

The first study, published in the journal SLEEP, analyzed the effects of nighttime light exposure—similar to that from televisions, phones, or streetlights—on circadian rhythms and brain changes associated with Alzheimer's. Findings showed that such light disrupted daily activity rhythms, leading to reduced stability and increased fragmentation. In Alzheimer's disease models, light exposure was linked to a modest increase in amyloid buildup and changes in microglial behavior toward a more activated immune state.

Adam Bachstetter, Ph.D., the lead author, noted, "These studies examine why sleep and daily biological rhythms become disrupted in Alzheimer's disease, and whether those disruptions are influenced by both the outside environment and inflammation inside the brain." An editorial accompanying the study emphasized artificial light at night as a potentially modifiable factor affecting Alzheimer's risk through circadian and neuroimmune pathways.

The second study, appearing in Alzheimer's & Dementia, evaluated the causes of poor sleep in Alzheimer's pathology. Researchers monitored sleep, activity rhythms, and inflammatory markers over time in models of Alzheimer's disease. They found that sleep disruption and fragmented rhythms appeared in midlife, even before significant memory loss occurred. Tests with a compound called MW151—developed by Linda Van Eldik, Ph.D.—showed improvement in sleep patterns and daily rhythms, without affecting amyloid levels. This suggests that inflammation might be a key factor driving sleep disturbances in Alzheimer's rather than amyloid alone.

Bachstetter stated, "We now know that sleep can be improved without reducing amyloid," indicating that neuroinflammatory signaling could be a modifiable contributor to poor sleep in Alzheimer's.

These findings are critical, as sleep disruptions are common in Alzheimer's and often occur years before severe cognitive symptoms appear. The research supports the idea that sleep and circadian health are vital in brain aging. Co-author Marilyn Duncan, Ph.D., pointed out that practical strategies, such as minimizing night-time light exposure, maintaining a regular sleep schedule, and supporting healthy circadian rhythms, align with current sleep health guidance.

The collaborative research at Sanders-Brown involves various disciplines, highlighting the integrated approach taken by the center's investigators and trainees.